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Bike mounted boombox

Fountek FR89ex-8, maybe? Never heard one, but it looks like it fits the bill. Needs about 2.25 liters per driver, plus 0.3-0.6 liters or so for a vent.
 
USspeaker.com (no affiliation) has the discontinued Faital 3" 3FE20 on blowout, 19$. It used to be ~35-40$ IIRC. Other 3" and 4" models from Faital could also be good and are priced up to ~35$ as well, check it out! Most of these have rather elevated Fs, ~100Hz or more, but they make up for it in good sensitivity for the size, ~90dB.

az
 
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Heh, I almost posted that Faital driver too, but I don't think it would really work without a high pass. Otherwise perfect, though.
 
doucanoe said:
Hey Lance, I'm not sure how dead set on buying something in particular, but I have a pair of potentially interesting 3" "full range" drivers sitting here doing nothing. I picked them up from Jerry thinking I would try them out for a little bookshelf pair for the bedroom but have yet to get around to doing anything with them. They were originally offered up as a full range closeout from Parts Express and folks were building them into 1/2 cu-ft cabs or something like that. I have the notes around here somewhere.

Paper cone I believe, but are heavy little buggers and have neoprene surrounds.






You are more than welcome to give them a go if interested.


RC
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Thanks for that offer, Ron. We should get together sooner rather than later.

dumptruck said:
Fountek FR89ex-8, maybe? Never heard one, but it looks like it fits the bill. Needs about 2.25 liters per driver, plus 0.3-0.6 liters or so for a vent.
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Yes:thmbsp:. This was one of my leading candidates. That aluminum cone would bring a lot of bling to the project and is a good material for the application.

DT, I know you're a really knowledgeable cat about drivers and what they do, dispersion and the like. Here's a question for 'ya, if you don't mind. What is the best grill covering for an application like this? I guess my requirements are that it not hold water against the driver, offer protection against hazard, and not block a lot of sound.

audiozaz said:
USspeaker.com (no affiliation) has the discontinued Faital 3" 3FE20 on blowout, 19$. It used to be ~35-40$ IIRC. Other 3" and 4" models from Faital could also be good and are priced up to ~35$ as well, check it out! Most of these have rather elevated Fs, ~100Hz or more, but they make up for it in good sensitivity for the size, ~90dB.

az
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AZ, you're the best!:yes: Just ordered two!:thmbsp:
That is the best candidate, so far. One feature it has that none of the others I've looked at have is the lesser mounting depth because of the neodymium magnet. With a mounting depth of only 1.5". it will allow for a 2" depth of the case (if I can get everything else jammed in there). I'll need to do some more design work and see how it will all fit and also accommodate the drivers.
I've pretty much figured that a 3" driver isn't going to put a lot of bass out there, enough to make it listenable, though. My shop speakers are the Fostex FE108 Sigma's and I find them adequate for my listening in the shop.

All you guys are the best!:thmbsp::thmbsp::thmbsp:
 
I assume that the Faital drivers might be able to take somewhat of a "light trashing" gracefully, but a high-pass before the amp would indeed be good as DT mentionned. I guess you'll see when you play them "in the field". 2nd or 3rd order would be best no to affect the ~100Hz level too much.

az
 
westend said:
DT, I know you're a really knowledgeable cat about drivers and what they do, dispersion and the like. Here's a question for 'ya, if you don't mind. What is the best grill covering for an application like this? I guess my requirements are that it not hold water against the driver, offer protection against hazard, and not block a lot of sound.
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Sorry, no ideas for you there, but I'm interested to see what you come up with since I'm working on outdoor boxes too.

Here's a 3FE20 simulation for you, in a slim vented box. The black line is axial response, dashed line is 45° off-axis. The 2mH+20Ω flattens the on-axis response (which rises 10dB above 500Hz without a filter). The part I left disconnected with 2uF and 16Ω is an add-on treble boost, to counteract the off-axis rolloff if wanted. Without a steep high pass, output should be limited by xmax to somewhere around 80-85dB or so for music, judging by the sim.

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Thanks again, guys. That kind of stuff is beyond good!:thmbsp::thmbsp: DT, do you remember the enclosure size you used for that sim?

I've now turned my attention towards what amp I'm going to use and have been looking over in the "Class D" section of DIYaudio. My initial idea is to use a T-amp board since they're cheap, run with 12v, and will drive a small cone with pretty good results. They're also well documented. I'm still looking....:scratch2::smoke:
 
Whatever you do, make sure it has blu-tooth connectivity. No wires and they can keep their phone in their pocket.
 
VinylHanger said:
Whatever you do, make sure it has blu-tooth connectivity. No wires and they can keep their phone in their pocket.
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I know......................this is one of those features that would probably be shot down in a marketing meeting because of the added expense but it makes the whole device a success. Dammit, now I've got another three hours of reading!:sigh::D
 
westend said:
DT, do you remember the enclosure size you used for that sim?
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That was 1.9 liters per driver, 100Hz. I didn't even try to optimize that part, though. I'd say that's more like the minimum. You could go way larger and extend the bass response a little. Probably even 10 times larger. Since SPL is being limited by excursion below Fb, it shouldn't cost much of anything but space to do so.
 
No help on the audio part here, but a suggestion for mounting hardware. ATV and snowmobile suppliers have all kinds of gizmos that clamp onto round tube frames and cargo racks. Most of the clamps are available separately and have a threaded hole for attachments. Once installed they are very secure, way better than velcro or bungee cords.
 
Considering efficiency to be a prime concern here versus a hi-fi damped bass response, 2L@100Hz is a good starting point IMO. You could probably lower tuning by ~10Hz for each extra liter in Vb, but I wouldn't go past 4L@80Hz myself and probably settle on 3L@90Hz or so.

az
 
dumptruck said:
That was 1.9 liters per driver, 100Hz. I didn't even try to optimize that part, though. I'd say that's more like the minimum. You could go way larger and extend the bass response a little. Probably even 10 times larger. Since SPL is being limited by excursion below Fb, it shouldn't cost much of anything but space to do so.
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Thanks! I will definitely be on the lower end of enclosure size.

jimbofish said:
No help on the audio part here, but a suggestion for mounting hardware. ATV and snowmobile suppliers have all kinds of gizmos that clamp onto round tube frames and cargo racks. Most of the clamps are available separately and have a threaded hole for attachments. Once installed they are very secure, way better than velcro or bungee cords.
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Ya, thanks. We here, at Westend Co., do not use bungee's or velcro unless it is absolutely imperative. I'll be checking out the ATV guys for clamps and such. I'd like a gizmo that has a pipe clamp on one end, has an articulating joint for swivel, and has a 1/4-20 threaded attachment point on the other end (this could be a flange with a 1/4" hole). The threads will allow a user to spin on the box like a camera and then lock it with a nut (threaded handle?).

audiozaz said:
Considering efficiency to be a prime concern here versus a hi-fi damped bass response, 2L@100Hz is a good starting point IMO. You could probably lower tuning by ~10Hz for each extra liter in Vb, but I wouldn't go past 4L@80Hz myself and probably settle on 3L@90Hz or so.

az
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2L sounds like a good target, maybe more apparent volume from some stuffing? Even 3L may be possible, depending on dimensions of the complete case. The Faital drivers will be here on Tues. so I'll be able to verify some measurements with how they fit onto the aluminum panel.

I've been turning my attention to the type of amp and sundry other bits needed for this project. The various offerings for the T-2020, T-2024, and T-2021 are all readily available and low in price. 12v LI-on battery packs with a walwart should be good for power. I'm commited to have this bluetooth enabled and board with that will be inside. I may have to include some power regulation to power the bluetooth board. For connectivity, I'm thinking of two phono RCA inputs or one stereo 1/8" jack.
Probably a mini-toggle for power interruption and I will be checking out what type of volume pot comes with the amp boards or if I'll be supplying that, too. A small LED indicator will be included.
Oh, think I found a good grill cover--an 80mm computer fan grill makes a handsome grill (I even have one that is gold plated :yes:).

I was trying to envision what type of small handle to use with this and my latest version is a "D" ring bolted onto the extruded T-track with a wrist lanyard/clip. What do you think of that? :scratch2:
 
westend said:
2L sounds like a good target, maybe more apparent volume from some stuffing? Even 3L may be possible, depending on dimensions of the complete case. The Faital drivers will be here on Tues. so I'll be able to verify some measurements with how they fit onto the aluminum panel.
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Stuffing will give up to 25% more apparent Vb in a sealed box, but doing so in a vented box is probably not a good idea, so I think this is pretty much WYSIWYG regarding Vb. Lining on the wall will reduce HF bouncing around, but won't do much towards extra Vb.

az
 
audiozaz said:
Stuffing will give up to 25% more apparent Vb in a sealed box, but doing so in a vented box is probably not a good idea, so I think this is pretty much WYSIWYG regarding Vb. Lining on the wall will reduce HF bouncing around, but won't do much towards extra Vb.

az
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Exactly, WYSIWYG is one of my fundamental design principles! I have a large roll of fine english felt so I know what the box will be lined with. If it fits the purpose, I'll throw in some other fiber. That will all be solved in the testing phase, I'm thinking.

thefragger said:
I backed thie product and it's been fantastic both on my bike and off.

http://www.kickstarter.com/projects/krissman/outdoor-techs-turtle-shell-rugged-wireless-boombox

1/2-20 thread mount (compatible with camera tripod), a clamp included, and waterproof.

:thmbsp:
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Cripes.........remember that black bandaid deal?:D

That looks to be a good product, Philip. At least it looks like it's being built by real people instead of off the desk of some Asian fab shop. :sigh:

There's a lot I like about the Turtle shell. It's definitely small and lightweight, looks to be durable, decent sound presentation, good bluetooth functionality (speaker phone thing is awesome), and the clamp is just how I would have built it except in alloy (maybe I need more trust in high impact plastic). Of all the ways the attachment could be made, it's bizarre that it is the identical thing.:scratch2:

It would be interesting to see the electronics involved with the Turtle shell. As a kickstarter do you get any literature about it?

I was getting up to speed on how I would implement bluetooth with the BB and think I have the circuits and power understood. There were some user reports of interference in the signal when using the Class T amps and powering from the same source. A DC-DC converter solves that. Now that I've seen that speakerphone functionality might be a great thing to have, I'll have to rework my thoughts on how many buttons are going to be needed.

It might be that the WYSIWYG team veto's buttons. Can't your phone be set to automatically interrupt audio playback. I don't use my phone for audio so don't have a clue. hey Philip, how busy are you? I might have to tender you an offer about working through the bluetooth thing. :D Either that, or how do I get my own kickstarter account?:nutz:
 
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Unfortunately no, there was no circuit diagrams or any literature involved. All I received were my speakers in their retail boxes, and I already tried prying one open, but they're really waterproof.

There's some turn on / turn off thump, but whatever, it's a neat thing all the same. Better than laptop speakers for a quick movie!

The bluetooth circuitry I'd image wants some pretty solid power supply regulation, as it's a low-power transmitter/receiver, and power supply noise would probably mess the whole RF side of things up. Honestly I'd do what you suggested with a DC-DC converter and use some BT earpiece's guts (then again I haven't done much research into this functionality--might be fun to have an 807 tube amp (I'm parting up quietly, shhh) with bluetooth connectivity... great, now you've got me thinking, Lance!)

Back to the turtleshell, it's gone the on/off switch, a USB and 3.5mm input jack both closed behind a watertight door-flap-thing, and three buttons: a play/pause, volume+/fwd, and a volume-/rrw (the alternate function is dependant on the duration that the button is held for).

There's also this neat product (that I'm look at potentially cloning a simpler version of) which uses only that thingy on the top of it: http://www.kickstarter.com/projects/tubecore/tubecore-duo (fairly certain it uses this titanium driver for their "stretch goal": http://www.parts-express.com/pe/showdetl.cfm?partnumber=264-916 )

It's pretty easy to sign up for KS, but I've never made a project before (stay tuned... ), so I can't help ya there.

Anyways, I'll check into the BT connectivity thing and I'll see what I can dig up. Ping me if I don't get back to you? There's a fair bit of stuff at work I'm taking on at the moment.
 
Philip, i was looking at these, mainly because others have had success:

Bluetooth module krc-86b

Some good information at DIYaudio says to split off from the amplifier power to the module using a DC-DC converter like this:

Murata DC-DC converter. That liittle converter is said to eliminate all of the interference resulting from any ground potential probs.

If there was any spurious RFI, that could be dealt with mechanically, I'm thinking.
 
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